Electrophysiological auditory responses and language development in infants with periventricular leukomalacia
This study presents evidence suggesting that electrophysiological responses to language-related auditory stimuli recorded at 46 weeks postconceptional age (PCA) are associated with language development, particularly in infants with periventricular leukomalacia (PVL). In order to investigate this hypothesis, electrophysiological responses to a set of auditory stimuli consisting of series of syllables and tones were recorded from a population of infants with PVL at 46 weeks PCA. A communicative development inventory (i.e., parent report) was applied to this population during a follow-up study performed at 14 months of age. The results of this later test were analyzed with a statistical clustering procedure, which resulted in two well-defined groups identified as the high-score (HS) and low-score (LS) groups. The event-induced power of the EEG data recorded at 46 weeks PCA was analyzed using a dimensionality reduction approach, resulting in a new set of descriptive variables. The LS and HS groups formed well-separated clusters in the space spanned by these descriptive variables, which can therefore be used to predict whether a new subject will belong to either of these groups. A predictive classification rate of 80% was obtained by using a linear classifier that was trained with a leave-one-out cross-validation technique.
from Brain and Language
The Effects of Age and Infant Hearing Status on Maternal Use of Prosodic Cues for Clause Boundaries in Speech
Conclusions: The results suggest that acoustic cues correlated with clause boundaries are available in maternal speech to HI infants. Their exaggeration relative to adult-directed speech suggests that mothers’ use of infant-directed speech is a natural behavior regardless of infant hearing status. Finally, mothers modify speech prosody according to their children’s age and hearing experience.
Our results indicate that syndromes associated with hearing loss and mechanical ventilation for more than 5 days were statistically significant risk factors in the occurrence of hearing loss. The most common risk factors are ototoxic medications, premature birth, low birth weight, and intensive care in excess of 7 days. As the number of risk factors an infant is exposed to grows, the probability of hearing impairment increases. The large percentage of children with sensorineural hearing loss in the absence of any known risk factors demonstrates the necessity of hearing examinations in all neonates.
Distributional information is a potential cue for learning syntactic categories. Recent studies demonstrate a developmental trajectory in the level of abstraction of distributional learning in young infants. Here we investigate the effect of prosody on infants’ learning of adjacent relations between words. Twelve- to thirteen-month-old infants were exposed to an artificial language comprised of 3-word-sentences of the form aXb and cYd, where X and Y words differed in the number of syllables. Training sentences contained a prosodic boundary between either the first and the second word or the second and the third word. Subsequently, infants were tested on novel test sentences that contained new X and Y words and also contained a flat prosody with no grouping cues. Infants successfully discriminated between novel grammatical and ungrammatical sentences, suggesting that the learned adjacent relations can be abstracted across words and prosodic conditions. Under the conditions tested, prosody may be only a weak constraint on syntactic categorization. Copyright © 2011 John Wiley & Sons, Ltd.
Incidence and clinical value of prolonged I–V interval in NICU infants after failing neonatal hearing screening
Infants admitted to neonatal intensive care units (NICUs) have a higher incidence of perinatal complications and delayed maturational processes. Parameters of the auditory brainstem response (ABR) were analyzed to study the prevalence of delayed auditory maturation or neural pathology. The prevalence of prolonged I–V interval as a measure of delayed maturation and the correlation with ABR thresholds were investigated. All infants admitted to the NICU Sophia Children’s Hospital between 2004 and 2009 who had been referred for ABR measurement after failing neonatal hearing screening with automated auditory brainstem response (AABR) were included. The ABR parameters were retrospectively analyzed. Between 2004 and 2009, 103 infants were included: 46 girls and 57 boys. In 58.3% (60 infants) of our population, the I–V interval was recordable in at least one ear at first diagnostic ABR measurement. In 4.9%, the I–V interval was severely prolonged. The median ABR threshold of infants with a normal or mildly prolonged I–V interval was 50 dB. The median ABR threshold of infants with a severely prolonged I–V interval was 30 dB. In conclusion, in case both peak I and V were measurable, we found only a limited (4.9%) incidence of severely prolonged I–V interval (≥0.8 ms) in this high-risk NICU population. A mild delay in maturation is a more probable explanation than major audiologic or neural pathology, as ABR thresholds were near normal in these infants.
There are few studies of infants and young children comparing ASSR thresholds to frequency-specific gold standard measures, especially using the multiple-ASSR technique. The present study, comparing multiple-ASSR to tone-ABR thresholds, nearly doubles the multiple-ASSR sample size in the literature. The results indicate that the multiple-ASSR and tone-ABR thresholds are strongly correlated, and the “normal” multiple-ASSR levels of 50, 45, 40, and 40 dB HL correctly classified children as having “normal” or “elevated” thresholds. However, due to the lack of air- and bone-conduction data in infants with different types and degrees of hearing loss, further ASSR research is needed.
The Detection of Infant Cortical Auditory Evoked Potentials (CAEPs) Using Statistical and Visual Detection Techniques
Hotelling’s T2 appears to detect CAEPs from normal hearing infants at a rate equal to that of an experienced examiner. A clinical instrument that applies Hotelling’s T2 on-line, so that the likelihood of response detection can be assessed objectively, should be of particular benefit to the novice or less experienced examiner.
Preliminary Temporal Measurement Analysis of Normal Oropharyngeal Swallowing in Infants and Young Children
Temporal measures of normal pediatric oropharyngeal deglutition have not been studied. Knowledge of range and variation of normative temporal measures could define abnormal deglutition and assist in design of appropriate compensatory and rehabilitative treatment techniques. The purpose of this retrospective study was to determine temporal measurements for oral filling, oral transit, onset of laryngeal closure, time of bolus arrival at the valleculae, pharyngeal delay, pharyngeal transit, and UES opening. Videofluoroscopic swallow studies of 15 normally swallowing pediatric subjects were divided into three age groups and method of liquid delivery. Mean, standard deviation, percentages, and extension of the median were utilized to determine relationships of temporal measures. Mean temporal duration increased with age for oral filling, oral transit time, time of laryngeal closure, UES opening, and pharyngeal delay time. However, no significant differences were found between age groups indicating a deglutitive biomechanical adaptation to growth of the oral and pharyngeal cavity. Feeding method for bottle versus cup mean duration increased for oral transit time, laryngeal closure time, UES opening, and pharyngeal delay time. Bolus head location relative to onset of laryngeal vestibule closure changed with increased age and method of feeding. Temporal measures were not significantly different for age groups or feeding methods. Bolus location was at or fully contained in the valleculae at the onset of laryngeal closure and appeared to be a normal finding in functional pediatric swallows and is not indicative of a delay or disorder.
The purpose of this study was to present a simple and powerful fitting model that describes age-dependent changes of auditory brainstem responses (ABR) in a clinical population of normal hearing children. A total of 175 children (younger than 200 weeks postconceptional age) were referred for audiologic assessment with normal ABR results. ABR parameters of normal hearing children between 2003 and 2008 were included. The results of the right ears recorded at 90 dB nHL were analyzed. A simple and accurate fitting model was formulated based on these data. A very similar age-dependent effect was found for peaks III and V, and I–III and I–V intervals; latencies decrease as postconceptional age increases. It shows that the total age-dependent effect will be completed after 1.5–2 years. The age-dependent effect can be modeled by a relatively simple and accurate exponential function. This fitting model can be easily implemented to analyze ABR results of infants in daily clinical practice. We speculate about the underlying physiological processes.
Effects of congenital hearing loss and cochlear implantation on audiovisual speech perception in infants and children
Cochlear implantation has recently become available as an intervention strategy for young children with profound hearing impairment. In fact, infants as young as 6 months are now receiving cochlear implants (CIs), and even younger infants are being fitted with hearing aids (HAs). Because early audiovisual experience may be important for normal development of speech perception, it is important to investigate the effects of a period of auditory deprivation and amplification type on multimodal perceptual processes of infants and children. The purpose of this study was to investigate audiovisual perception skills in normal-hearing (NH) infants and children and deaf infants and children with CIs and HAs of similar chronological ages.
CONCLUSION: the ASSR can provide accurate information to support the selection of hearing aids for children when it is not possible to perform the VRA.
Effects of Universal Newborn Hearing Screening on an Early Intervention Program for Children with Hearing Loss, Birth to 3 Yr of Age
UNHS had a positive impact on caseload size, age of diagnosis, age of enrollment in EI, and age of hearing aid fit. The percentage of the caseload identified in the newborn period was about 25% before UNHS and over 80% after its implementation. After UNHS, the EI caseload included as many children with mild and moderate hearing loss as with severe and profound loss. By the last reporting year in the study (academic year 2005-2006) all children with profound hearing losses had cochlear implants.
In order to acquire their native language, infants must learn to identify and segment word forms in continuous speech. This word segmentation ability is thus crucial for language acquisition. Previous behavioral studies have shown that it emerges during the first year of life, and that early segmentation differs according to the language in acquisition. In particular, linguistic rhythm, which differs across classes of languages, has been found to have an early impact on segmentation abilities. For French, behavioral evidence showed that infants could use the rhythmic unit appropriate to their native language (the syllable) to segment fluent speech by 12 months of age, but failed to show whole word segmentation at that age, a surprising delay compared to the emergence of segmentation abilities in other languages. Given the implications of such findings, the present study reevaluates the issue of whole word and syllabic segmentation, using an electrophysiological method, high-density ERPs (event-related potentials), rather than a behavioral technique, and by testing French-learning 12-month-olds on bisyllabic word segmentation. The ERP data show evidence of whole word segmentation while also confirming that French-learning infants rely on syllables to segment fluent speech. They establish that segmentation and recognition of words/syllables happen within 500 milliseconds of their onset, and raise questions regarding the interaction between syllabic segmentation and multisyllabic word recognition.
from Brain Research
Perceptual grouping has traditionally been thought to be governed by innate, universal principles. However, recent work has found differences in Japanese and English speakers’ non-linguistic perceptual grouping, implicating language in non-linguistic perceptual processes (Iversen, Patel, & Ohgushi, 2008). Two experiments test Japanese- and English-learning infants of 5–6 and 7–8 months of age to explore the development of grouping preferences. At 5–6 months, neither the Japanese nor the English infants revealed any systematic perceptual biases. However, by 7–8 months, the same age as when linguistic phrasal grouping develops, infants developed non-linguistic grouping preferences consistent with their language’s structure (and the grouping biases found in adulthood). These results reveal an early difference in non-linguistic perception between infants growing up in different language environments. The possibility that infants’ linguistic phrasal grouping is bootstrapped by abstract perceptual principles is discussed.
Method: Twenty-seven children (11 with normal hearing, 16 with impaired hearing) between 11 and 78 months of age were video recorded in naturalistic settings for analyses of head orientation. Reports on daily activities were obtained from caregivers. The effect of directionality in different environments was quantified by measuring the Speech Transmission Index (STI; H. J. M. Steeneken & T. Houtgast, 1980).
Results: Averaged across 4 scenarios, children looked in the direction of a talker for 40% of the time when speech was present. Head orientation was not affected by age or hearing status. The STI measurements revealed a directional advantage of 3 dB when a child looked at a talker but a deficit of 2.8 dB when the talker was sideways or behind the child. The overall directional effect in real life was between –0.4 and 0.2 dB.
Conclusions: The findings suggest that directional microphones in personal hearing devices for young children are not detrimental and have much potential for benefits in real life. The benefits may be enhanced by fitting directionality early and by counseling caregivers on ways to maximize benefits in everyday situations.